The aforementioned linear units are used, in particular, in “active” brake systems, in which brake pressure can be built up independently or in support of the brake actuation by the driver. In this case a linear unit, for example, translates a rotational motion of a threaded spindle into a linear motion of a threaded nut. The resulting travel of the threaded nut can then be used to move a piston and thereby to build up brake pressure in one or more brake circuits, particularly by hydraulic means. Here the spindle may be connected to the shaft of an electric motor, which is activated by an electronic control unit (ECU) in order to increase and/or reduce the pressure.
Linear units as described above are disclosed by DE 10 2009 019 209 A1 or DE 10 2010 039 916 A1, for example.
WO 2011/029812 discloses a brake system for motor vehicles, which as a pressure-generating device having a hydraulic cylinder-piston arrangement, the piston of which can be actuated by an electric motor by way of a rotational/linear translation mechanism. In the “brake-by-wire” operating mode the system pressure is built up by this linear actuator.
Technical developments of linear units are known in which the nut is connected to the profiled tube by way of an adapter or a sleeve, the connection between the sleeve and the nut being lasered and the connection between the profiled tube and the sleeve being calked. In the known construction, therefore, more components and connections are needed in order to connect the profiled tube and the nut together.
The object of the invention, therefore, is to improve a linear unit for a brake system for motor vehicles so that fewer components are needed than hitherto and the assembly of the linear unit is kept as simple as possible. A further object is to specify a corresponding method of manufacture.